Still Puzzling Over Those Pennies?

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Marilyn

I saved the penny-grouping problem because a friend and I found your solution hard to believe. (March 6, 2016) But we tried it three times, and it worked every time. We are puzzled as to why. Can you explain?

—Jim Durkee in Belton, Texas

One good way to see why the solution works is to watch your friend perform the actions. Or perform the actions yourself with your eyes open instead of closed.